Model-based testing is a technique used to test or debug software. With model-based testing, a description, or model, is created that captures the behavior of a software or system being tested. From this description, any number of test cases can be automatically generated and executed on the software to verify the software's quality or behavior. However, when a defect or undesirable condition is found in a test case, it can be difficult for software testers to isolate and diagnose the problem. Only a few unknown execution steps may be responsible for causing a condition of interest, such as an error condition, a fault, an unexpected result, etc. Those few steps in the test case that are essential to exposing the program's condition may be scattered among thousands of extraneous steps. Identifying them can be difficult, yet isolation and diagnosis of causes of the condition is easier when extraneous execution steps are eliminated.